This week will not involve an outside speaker, but will instead be
a general discussion of a topic that many regular participants have asked
be explored in an open forum. The topic will be explored with a series
of questions, including what the relative rates of evolution at different
levels of selection, how to test for evidence of complex adaptations produced
by selection at different levels of selection, and possible instances of
group selection from parasitic infections in hosts, to warrior castes in
eusocial insect species whose queens engage in multiple matings, to D.S.
Wilson's reanalyses of reciprocity and kin selection as instances of group
selection, to putatitive human cases.

For background, attendees are encouraged to consult George William's
Adaptation and Natural Selection, and for a more recent and opposed
view, David Sloan Wilson's and Eliot Sober's paper in Behavioral and
Brain Sciences, "Re-Introducing
Group Selection To The Human BehavioralSciences"
(the on-line version is without the commentary).

Wilson & Sober Abstract

"In both biology and the human sciences, social groups are sometimes
treated as adaptive units whose organization cannot be reduced to individual
interactions. This group-level view is opposed by a more individualistic
view that treats social organization as a byproduct of self-interest. According
to biologists, group-level adaptations can evolve only by a process of
natural selection at the group level. During the 1960's and 70's most biologists
rejected group selection as an important evolutionary force but a positive
literature began to grow during the 70's and is rapidly expanding today.
We review this recent literature and its implications for human evolutionary
biology. We show that the rejection of group selection was based on a misplaced
emphasis on genes as "replicators" which is in fact irrelevant to the question
of whether groups can be like individuals in their functional organization.
The fundamental question is whether social groups and other higher-level
entities can be "vehicles" of selection. When this elementary fact is recognized,
group selection emerges as an important force in nature and ostensible
alternatives, such as kin selection and reciprocity, reappear as special
cases of group selection. The result is a unified theory of natural selection
that operates on a nested hierarchy of units."

"The vehicle-based theory makes it clear that group selection is an
important force to consider in human evolution. Humans can facultatively
span the full range from self-interested individuals to "organs" of group-level
"organisms." Human behavior not only reflects the balance between levels
of selection but it can also alter the balance through the construction
of social structures that have the effect of reducing fitness differences
within groups, concentrating natural selection (and functional organization)
at the group level. These social structures and the cognitive abilities
that produce them allow group selection to be important even among large
groups of unrelated individuals. "